Stoichiometric Control of Electrocatalytic Amorphous Nickel Phosphide to Increase Hydrogen Evolution Reaction Activity and Stability in Acidic Medium

Abstract

This work describes the electrocatalysis of amorphous nickel phosphide (Ni‐P) electrodeposited onto copper metal foil, for its use as a non‐noble metal catalyst for the hydrogen evolution reaction (HER) in 0.5 M H2SO4. Although electrodeposition offers many advantages over conventional high temperature and high pressure fabrication techniques, there are very few reports on the preparation of Ni‐P electrocatalysts via electrodeposition. This Ni‐P electrocatalyst exhibits good activity in acidic medium, with a potential of –222 mV to achieve 10 mA cm–2 cathodic current density. This potential is comparable to that of electrodeposited Pt black (–104 mV), and much better than that of electrodeposited Ni (–480 mV). An unusual long‐term stability in acidic medium was demonstrated by the –222 mV potential remaining constant after 5000 cyclic voltammetric sweeps in 0.5 M H2SO4. Importantly, the stoichiometry of the nickel phosphide films can be easily varied from an atomic % of phosphorus from 15 % to as high as 24 % by modifications to the electrodeposition conditions. Such a high phosphorous loading is greater than is generally reported with electrodeposited Ni‐P materials. In addition, we observed Ni‐P films electrodeposited at lower temperatures (∼ 3 °C) result in higher phosphorous loading, which gives rise to enhanced stability as well as activity. Electrodeposited amorphous Ni‐P can therefore be used as an active, stable and Earth‐abundant metal catalyst for the HER in acidic electrolytes.

Three-Dimensional Dendritic Cu–Co–P Electrode by One-Step Electrodeposition on a Hydrogen Bubble Template for Hydrogen Evolution Reaction

“…The high-resolution spectrum of P 2p is divided into two types of phosphide species of oxidized and elemental P. The reason that oxidized P was observed is the surface passivation. 50,51 The P 2p spectral peaks from Cu−Co−P appear at 133.9 eV and 130 eV and are negatively shifted by −0.2 eV relative to the known position of elemental P (130.2 eV). 52 To confirm the change of chemical state of Cu−Co−P 20 after the durability test, we measured the XPS in Figure S12.…”

“…The Co 2p 3/2 in both Cu–Co and Cu–Co–P 20 was observed as metallic Co (Co 0 (778.25 eV) and Co δ+ (778.55 eV)) and oxidized Co 2+ /Co 3+ (781.9 eV/779.7 eV and 782.4 eV/780.3 eV) with satellite (786.7 eV and 787.2 eV). The oxidized metals are common when the TMPs are exposed to air condition . When comparing Cu–Co and Cu–Co–P 20 , binding energy shift of Cu and Co was observed in the positive direction.…”

Nickel Phosphide Electrocatalysts for Hydrogen Evolution Reaction

“…As-prepared nickel/nickel phosphide/carbon cloth electrodes exhibit a cathodic current of 10 mA/cm 2 at the overpotential of 164 mV in a 0.5 M H 2 SO 4 solution and a Tafel slope of 76 mV/dec. Wasalathanthri et al prepared amorphous nickel phosphide thin films on Cu foil by electrodeposition at a constant current density of 10 mA/cm 2 for 10 min, which exhibits a good activity and long-term stability in acidic medium, with a potential of −222 mV to achieve 10 mA/cm 2 [140]. Wang et al reported the preparation of amorphous sponge-like nickel phosphide-carbon nanotube (Ni x P/CNT) hybrid electrodes through CV deposition [143].…”

Electrodeposited Copper–Cobalt–Phosphide: A Stable Bifunctional Catalyst for Both Hydrogen and Oxygen Evolution Reactions

“…Enhancing energy conversion and storage systems, such as water electrolysis, fuel cells, and metal–air batteries, are needed for clean and efficient alternate energy sources − and to reduce pollution that is harmful to human health . These systems involve either hydrogen evolution reaction (HER) or oxygen reduction reaction (ORR) at the cathode, and oxygen evolution reaction (OER) or oxidation of fuels at the anode .…”

“…A variety of transition metal chalcognides − and phosphides ,,,− exhibit high HER activity. Owing to their higher affinity toward H 2 , transition metal phosphides (TMPs) are also excellent catalysts in other processes, such as hydrodesulfurization, hydrodenitrification, and CO hydrogenation, indicating a vast applicability of TMP HER catalysts .…”